An Approximate Geodesic Distance Tree Filter for Cost Aggregation

Abstract Three-dimensional (3D) reconstruction is extensively used in microscopic applications. Reducing excessive error points and achieving accurate matching of weak texture regions have been the classical challenges for 3D microscopic vision. A Multi-ST algorithm was proposed to improve matching accuracy. The process is performed in two main stages: scaled microscopic images and regularized cost aggregation. First, microscopic image pairs with different scales were extracted according to the Gaussian pyramid criterion. Second, a novel cost aggregation approach based on the regularized multi-scale model was implemented into all scales to obtain the final cost. To evaluate the performances of the proposed Multi-ST algorithm and compare different algorithms, seven groups of images from the Middlebury dataset and four groups of experimental images obtained by a binocular microscopic system were analyzed. Disparity maps and reconstruction maps generated by the proposed approach contained more information and fewer outliers or artifacts. Furthermore, 3D reconstruction of the plug gauges using the Multi-ST algorithm showed that the error was less than 0.025 mm.

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Novel geodesic distance Fourier shape descriptor

Journal of Computer Applications ◽

10.3724/sp.j.1087.2010.00362 ◽

2010 ◽

Vol 30 (2) ◽

pp. 362-363

Author(s):

Sheng CHEN ◽

Xun LIU

Keyword(s):

Geodesic Distance ◽

Shape Descriptor

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Some Information Geometric Aspects of Cyber Security by Face Recognition

Entropy ◽

10.3390/e23070878 ◽

2021 ◽

Vol 23 (7) ◽

pp. 878

Author(s):

C. T. J. Dodson ◽

John Soldera ◽

Jacob Scharcanski

Keyword(s):

Face Recognition ◽

Cyber Security ◽

Probability Distributions ◽

Geodesic Distance ◽

Recognition Method ◽

Frequency Distributions ◽

Face Images ◽

User Access ◽

Multidimensional Methods ◽

Joint Probabilities

Secure user access to devices and datasets is widely enabled by fingerprint or face recognition. Organization of the necessarily large secure digital object datasets, with objects having content that may consist of images, text, video or audio, involves efficient classification and feature retrieval processing. This usually will require multidimensional methods applicable to data that is represented through a family of probability distributions. Then information geometry is an appropriate context in which to provide for such analytic work, whether with maximum likelihood fitted distributions or empirical frequency distributions. The important provision is of a natural geometric measure structure on families of probability distributions by representing them as Riemannian manifolds. Then the distributions are points lying in this geometrical manifold, different features can be identified and dissimilarities computed, so that neighbourhoods of objects nearby a given example object can be constructed. This can reveal clustering and projections onto smaller eigen-subspaces which can make comparisons easier to interpret. Geodesic distances can be used as a natural dissimilarity metric applied over data described by probability distributions. Exploring this property, we propose a new face recognition method which scores dissimilarities between face images by multiplying geodesic distance approximations between 3-variate RGB Gaussians representative of colour face images, and also obtaining joint probabilities. The experimental results show that this new method is more successful in recognition rates than published comparative state-of-the-art methods.

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A Joint 2D-3D Complementary Network for Stereo Matching

Sensors ◽

10.3390/s21041430 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1430

Author(s):

Xiaogang Jia ◽

Wei Chen ◽

Zhengfa Liang ◽

Xin Luo ◽

Mingfei Wu ◽

...

Keyword(s):

Stereo Matching ◽

Computational Cost ◽

Research Field ◽

Disparity Map ◽

Improve Performance ◽

Cost Aggregation ◽

Disparity Range ◽

Public Datasets ◽

Coarse To Fine ◽

Speed And Accuracy

Stereo matching is an important research field of computer vision. Due to the dimension of cost aggregation, current neural network-based stereo methods are difficult to trade-off speed and accuracy. To this end, we integrate fast 2D stereo methods with accurate 3D networks to improve performance and reduce running time. We leverage a 2D encoder-decoder network to generate a rough disparity map and construct a disparity range to guide the 3D aggregation network, which can significantly improve the accuracy and reduce the computational cost. We use a stacked hourglass structure to refine the disparity from coarse to fine. We evaluated our method on three public datasets. According to the KITTI official website results, Our network can generate an accurate result in 80 ms on a modern GPU. Compared to other 2D stereo networks (AANet, DeepPruner, FADNet, etc.), our network has a big improvement in accuracy. Meanwhile, it is significantly faster than other 3D stereo networks (5× than PSMNet, 7.5× than CSN and 22.5× than GANet, etc.), demonstrating the effectiveness of our method.

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WEIGHTED AVERAGE GEODESIC DISTANCE OF PENTADENDRITE NETWORKS

Fractals ◽

10.1142/s0218348x20500759 ◽

2020 ◽

Vol 28 (05) ◽

pp. 2050075

Author(s):

YUANYUAN LI ◽

XIAOMIN REN ◽

KAN JIANG

Keyword(s):

Complex Networks ◽

Geodesic Distance ◽

Average Distance ◽

Weighted Average ◽

Similar Measure ◽

Important Index ◽

Self Similar

The average geodesic distance is an important index in the study of complex networks. In this paper, we investigate the weighted average distance of Pentadendrite fractal and Pentadendrite networks. To provide the formula, we use the integral of geodesic distance in terms of self-similar measure with respect to the weighted vector.

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Real-time deep learning semantic segmentation during intra-operative surgery for 3D augmented reality assistance

International Journal of Computer Assisted Radiology and Surgery ◽

10.1007/s11548-021-02432-y ◽

2021 ◽

Author(s):

Leonardo Tanzi ◽

Pietro Piazzolla ◽

Francesco Porpiglia ◽

Enrico Vezzetti

Keyword(s):

Neural Network ◽

Deep Learning ◽

Augmented Reality ◽

Ad Hoc ◽

Geodesic Distance ◽

Semantic Segmentation ◽

Endoscopic Image ◽

Operative Surgery ◽

Endoscopic Videos

Abstract Purpose The current study aimed to propose a Deep Learning (DL) and Augmented Reality (AR) based solution for a in-vivo robot-assisted radical prostatectomy (RARP), to improve the precision of a published work from our group. We implemented a two-steps automatic system to align a 3D virtual ad-hoc model of a patient’s organ with its 2D endoscopic image, to assist surgeons during the procedure. Methods This approach was carried out using a Convolutional Neural Network (CNN) based structure for semantic segmentation and a subsequent elaboration of the obtained output, which produced the needed parameters for attaching the 3D model. We used a dataset obtained from 5 endoscopic videos (A, B, C, D, E), selected and tagged by our team’s specialists. We then evaluated the most performing couple of segmentation architecture and neural network and tested the overlay performances. Results U-Net stood out as the most effecting architectures for segmentation. ResNet and MobileNet obtained similar Intersection over Unit (IoU) results but MobileNet was able to elaborate almost twice operations per seconds. This segmentation technique outperformed the results from the former work, obtaining an average IoU for the catheter of 0.894 (σ = 0.076) compared to 0.339 (σ = 0.195). This modifications lead to an improvement also in the 3D overlay performances, in particular in the Euclidean Distance between the predicted and actual model’s anchor point, from 12.569 (σ= 4.456) to 4.160 (σ = 1.448) and in the Geodesic Distance between the predicted and actual model’s rotations, from 0.266 (σ = 0.131) to 0.169 (σ = 0.073). Conclusion This work is a further step through the adoption of DL and AR in the surgery domain. In future works, we will overcome the limits of this approach and finally improve every step of the surgical procedure.

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FINDING AN OPTIMAL BRIDGE BETWEEN TWO POLYGONS

International Journal of Computational Geometry & Applications ◽

10.1142/s0218195902000852 ◽

2002 ◽

Vol 12 (03) ◽

pp. 249-261 ◽

Cited By ~ 1

Author(s):

XUEHOU TAN

Keyword(s):

Hierarchical Structure ◽

Shortest Path ◽

Line Segment ◽

Euclidean Distance ◽

Geodesic Distance ◽

Simple Polygon ◽

Time Algorithm ◽

Search Trees ◽

Bridge Problem ◽

Path Queries

Let π(a,b) denote the shortest path between two points a, b inside a simple polygon P, which totally lies in P. The geodesic distance between a and b in P is defined as the length of π(a,b), denoted by gd(a,b), in contrast with the Euclidean distance between a and b in the plane, denoted by d(a,b). Given two disjoint polygons P and Q in the plane, the bridge problem asks for a line segment (optimal bridge) that connects a point p on the boundary of P and a point q on the boundary of Q such that the sum of three distances gd(p′,p), d(p,q) and gd(q,q′), with any p′ ∈ P and any q′ ∈ Q, is minimized. We present an O(n log 3 n) time algorithm for finding an optimal bridge between two simple polygons. This significantly improves upon the previous O(n2) time bound. Our result is obtained by making substantial use of a hierarchical structure that consists of segment trees, range trees and persistent search trees, and a structure that supports dynamic ray shooting and shortest path queries as well.

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